Stackable chair with modular slide-on seat back

ABSTRACT

A stackable chair includes first, second, and third frame members. Each of the first and second frame members forms a front and rear chair leg joined by a seat side rail. The third frame member has opposed side portions respectively joined to the seat side rails, a transverse front nose portion, and a pair of upwardly-extending back stiles. A cushioned and upholstered seat module assembly is attached to the seat side rails. A back module assembly includes a contoured, cushioned, and upholstered back base element having a pair of channels formed therein that are configured and located so as to receive and conceal the stiles when the back module assembly is slid onto the stiles, whereby the back module assembly is attachable to the stiles along the channels. A lower lumbar support element is advantageously attached to the lower portion of the back base element.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit, under 35 U.S.C. Section 119(e), of co-pending provisional application No. 60/515,724, filed Oct. 30, 2003, the disclosure of which is incorporated by reference.

FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

(Not Applicable)

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to generally to the field of commercial and institutional furniture. In particular, the present invention, in one aspect, relates to a stackable chair having a modular, fully upholstered, multi-contoured, composite, slide-on seat back that requires no visible structural supports or fasteners for its assembly. In another aspect, the present invention relates to a method for assembling the seat back of the chair.

2. Related Art

Consumers of modern commercial and institutional furniture demand comfort, durability, and style in their seating choices, and in view of the highly competitive nature of the furniture industry, they also require that such choices be cost-effective as well. Additionally, many consumers want a “modern” appearance in their furniture, i.e., one that incorporates current styling, materials, manufacturing processes and assembly techniques. Thus, in commercial and institutional environments, such as in hotels, convention centers, hospitals, funeral parlors, restaurants, auditoriums, sanctuaries, and the like, a premium is placed on the comfort, durability and style of the furniture deployed therein.

For example, a stackable chair must be both comfortable to sit in, because of the prolonged sitting activities engaged in by the consumers' clients during business meetings, seminars, religious services and the like, and at the same time, robust and rugged, because of the stresses imposed on the chair as a result of being thrown, slid, kicked, dropped, stood-on, stacked, etc., by the consumers' employees and clients. The chair must also be appealing to the eye, affordable, and easily maintainable over many years of hard service.

The typical stackable chair commonly found in commercial and institutional settings uses a composite tubular frame that is configured to define four legs and two stiles, or uprights for the back. A seat assembly and a seat back assembly are attached to the frame. These assemblies typically include a composite (i.e., wood or plastic) base, a foamed elastomer cushioning material applied to the bases, and a cloth or plastic sheet type of upholstery covering applied over the elastomer cushioning. The two assemblies are respectively attached to the frame above the legs and between the uprights, typically with screw-type fasteners that extend through the frame and into the base of the respective assemblies.

Suppliers to the institutional/commercial furniture customer thus typically provide a fully assembled and upholstered seat back assembly having internal tubular channels on either side thereof. These internal channels are slid down over the composite frame uprights and attached to it with fasteners. The typical seat back assembly consists of a composite base (e.g., plywood), a plurality of captivated nuts (e.g., “T-nuts”) disposed in or through the base, a pair of square composite tubes (defining the bilateral internal mounting channels of the back), a plurality of fasteners (e.g., pan head machine screws), an optional lumbar support block (typically flat wood), a foamed elastomer cushioning material that has been slotted to accommodate the square composite mounting tubing, and some form of upholstering material covering the foamed elastomer cushions.

Assembly of the prior art seat back consists of cutting the base to size, drilling holes in the base for the captivated nuts, and installing the nuts therein. Tabs may be welded or bonded to the mounting tubes, and the base then attached to the tubes through the tabs with fasteners. The optional lumbar support block is attached to a lower portion of the base, again, typically, with a number of fasteners. The foamed elastomer cushion is glued and/or stapled to the base, and the entire assembly is then stuffed into an upholstered fabric covering.

The foregoing seat back configuration and method of its assembly provide a stackable chair having compressive and lateral strengths that are marginally satisfactory at their initial deployment. However, some problems have been found to exist with this type of seat back assembly over time or with hard use. For example, because of the nature of the typical environment in which a stackable chair is used, including its constant handling and mishandling over a relatively short period of time, the fasteners used to hold the seat back assembly to the frame can loosen, and eventually, migrate out of their installation holes. As will be appreciated, loose or lost seat back fasteners can result not only in damage to the chair, but an uncomfortable or even dangerous sitting experience for the client, as well.

Another problem with prior art stackable chairs involves their lack of comfort. Because of the base material typically used in the seat back (i.e., solid wood or plywood), the back cannot be easily configured to accommodate the multiple contours of the human back, particularly the lumbar region. Because of this, the back of a person sitting in a conventional stackable chair over even a short period of time can become very stressed and painful.

Additionally, stackable chairs incorporating current assembly techniques require the use of relatively dense woods or composite materials that are too heavy and cumbersome to be lifted and/or efficiently stacked for storage.

A long-felt but as yet unsatisfied need therefore exists in the field of commercial and institutional furniture for a stackable chair that is easily and inexpensively manufactured and assembled, and that has a seat back that can be easily and reliably installed without fasteners that can come loose during hard use. The seat back should be capable of incorporating multiple contours to conform ergonomically to the human back, and it should also be capable of being fully upholstered. Additionally, the upright supports of the frame of the chair should be completely hidden for an overall “clean” appearance of the chair.

SUMMARY OF THE INVENTION

Broadly, the present invention is a stackable chair having fully-upholstered, multi-contoured, polymer composite seat back assembly. The seat back is easily and inexpensively manufactured and assembled to the frame of the chair in a slide-on manner, with no structural supports or fasteners being visible after assembly. The novel chair provides comfort, durability, style and cost-effectiveness as a result of its incorporation of molded-in components that reduce material and labor costs. Additionally, the novel seat back weighs considerably less than those incorporated in prior art stackable chairs, such that lifting and stacking of the chair are easier and less strenuous.

In an exemplary embodiment, the chair comprises a plurality of subassemblies, or modules, that are fastened together to form the chair, including a frame module, a seat module, and a seat back module. The frame module comprises a pair of generally inverted U-shaped tubular side frame members, and a unitary tubular seat and back frame member. The three tubular members are preferably formed of steel or aluminum tubes, with open ends.

Each of the side frame members includes a pair of substantially vertical portions that form a front chair leg and a rear chair leg, respectively. The legs are connected by a longitudinal portion of the side frame member that extends front-to-back, substantially horizontally or at a slight downward angle from front to rear, thereby forming a seat side rail.

The seat and back frame member includes a pair of parallel elements, the front portions of which extend longitudinally (front to back) and are oriented substantially horizontal, or at a slight downward angle from front to rear. The rear portions of the parallel elements of the seat and back frame member are bent upward to define a pair of parallel, upstanding stile portions on which the seat back module of the chair is supported in a slide-on arrangement, as described below. The parallel elements of the seat and back frame member are connected at the front by a horizontal transverse element that defines a nose, or front rail, of the chair. The longitudinal portion of each of the side frame members is joined to a longitudinal portion of the seat and back frame member, such that the latter is rigidly supported therebetween. The assembly is held in a square, parallel, upstanding relationship by a pair of front and rear stretchers, or torsion bars, that respectively extend between the front chair legs and the rear chair legs. A plastic glide having an arcuate lower end snaps into the lower end of each the legs to prevent marring of a floor on which the chair is placed or slid.

The seat module comprises a molded composite seat base having a plurality of die cut foamed elastomer, e.g., polyurethane, layers bonded to it. The upper and side surfaces of the cushion material are covered by a woven fabric upholstery that overlaps the seat base, and the assembly is attached atop the substantially horizontal portions of the side frame members and the seat and back frame member by conventional threaded fasteners.

The novel seat back module comprises an arcuate, generally rectangular, molded composite, tray-like back base structure incorporating relatively thin, substantially solid back and side walls, and an open front face. It is internally divided and reinforced in an egg-crate fashion by a plurality of intersecting, upstanding webs that extend from the back wall to the open front face. The base of the back also defines a bilateral pair of tubular receptacles having open bottom ends and closed top ends which respectively slide down over respective ones of the upstanding stiles of the frame to firmly mount the back thereon. The back base is locked in place on the stiles by a pair of threaded fasteners that extend through the side of the base and into respective receptacles in the stiles.

A molded plastic lower lumbar support, having a substantially straight lower end and an upper end with a curvature matching that of the front face of the back structure, attaches to the lower portion of the front face of the back base by means of a plurality of molded resilient tabs that engage in corresponding slots molded into the back base in a snap-in, over-center locking engagement. The outside face of the lower lumbar support subassembly is covered with a fabric upholstery. A pair of foamed elastomer cushions, respectively corresponding to the upper portion of the front face of the back base and the upper lumbar region of an occupant of the chair, are bonded to the open front face of the back structure. The cushions, back surface and sides of the back structure are then covered in a fabric upholstery that includes robust tack strips that extend through the back base, such that the upstanding chair stiles are not visible, and the entire seat back module presents a finished, upholstered appearance.

A better understanding of the above and many other features and advantages of the invention may be had from a consideration of the detailed description below, in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an exemplary embodiment of a stackable chair in accordance with the present invention, showing the various modules thereof;

FIG. 2 is an enlarged partial detail view, as outlined in the circle “A” of FIG. 1, of a frame module of the chair;

FIG. 3 is an enlarged partial detail view, as outlined the circle “B” of FIG. 1, of a glide of the chair;

FIG. 4 is a perspective detail view of the glide of FIG. 4;

FIG. 5 is an enlarged partial detail view, as outlined in the circle “C” of FIG. 1, of an upholstery covering of a back module of the chair, showing a portion of a tack strip thereof;

FIG. 6 is an exploded perspective view of the chair, showing a seat module assembled to the frame module, and the back module before its assembly thereon;

FIG. 7 is an exploded perspective view of the chair similar to FIG. 6, showing the back module partially assembled to the frame module, and a lumbar support element before its assembly thereon;

FIG. 8 is a perspective view of the chair similar to FIGS. 6 and 7, showing the seat module and the back module fully assembled to the frame module of the chair;

FIGS. 9A-9E are perspective views of the chair, showing the sequential assembly of the structural parts of the back module thereon;

FIG. 10 is a detailed perspective view of the structural elements of the back module attached to the frame of the chair;

FIG. 11 is front elevational view of back base element of the chair;

FIG. 12 is a top plan view of the back base element of the chair;

FIG. 13 is a cross-sectional view taken along line 13-13 of FIG. 11;

FIG. 14 is a front perspective view of the back base element of FIG. 11;

FIG. 15 is a top plan view of the lumbar support element used in the back module of FIG. 10;

FIG. 16 is a rear elevational view of the lumbar support element;

FIG. 17 is a cross-sectional view taken along line 17-17 of FIG. 16;

FIG. 18 is a rear face perspective view of the lower lumbar support element;

FIG. 19 is a front elevation view of the chair, showing the back base element and the lumbar support element assembled thereto; and

FIG. 20 is a cross-sectional view of the chair taken along the line 20-20 of FIG. 19.

DETAILED DESCRIPTION OF THE INVENTION

An exploded perspective view of an exemplary embodiment of a stackable chair 10 in accordance with the present invention is illustrated in FIG. 1. As illustrated therein, the chair comprises a plurality of assemblies, or modules, including a frame module 12, a seat module 14, and a back module 16.

As illustrated in detail A of FIG. 1 and the enlarged view thereof of FIG. 2, the frame module 12 comprises a pair of generally inverted U-shaped tubular side frame members 18, and a tubular seat and back frame member 20. The tubular members 18 and 20 are preferably formed of steel or aluminum tubing, with open ends, and, as illustrated, they are generally square in cross-section. It will be appreciated, however, that that other cross-sectional shapes are possible, and may be preferable, depending on the application at hand.

Each of the side frame members 18 includes a pair of substantially vertical portions, each of which forms a front chair leg 22 a and a rear chair leg 22 b. Each front leg 22 a and rear leg 22 b is joined by a longitudinal (front-to-back) portion 23 of the side frame member 18 that is oriented substantially horizontally, or with a slight downward angle from front to rear, thereby forming a seat side rail.

The seat and back frame member 20 includes a pair of parallel elements, the front portions of which extend longitudinally and are oriented substantially horizontally, or at a slight downward angle from front to rear. The rear portions of the parallel elements of the seat and back frame member 20 are bent upward at an angle to define a pair of parallel, upstanding stiles 24. The front portions of the parallel elements of the seat and back frame member 20 are joined at the front by a horizontal, transverse portion that defines a “nose” portion, or front seat rail 26, of the chair (see also FIG. 10).

The longitudinal portions 23 of the side frame members 18 of the frame module 12 are respectively joined to respective ones of the corresponding longitudinal portions of the seat and back frame member 20 by a plurality of conventional fasteners (not shown), such that the seat and back frame member 20 is rigidly supported between the two side frame members 18, with the nose portion 26 facing forward. As illustrated in FIG. 2, the frame module 12 is held in a rigid, square, parallel, upstanding relationship by a pair of front and rear stretchers, or torsion bars 28, that respectively extend between and couple together the front chair legs 22 a and the rear chair legs 22 b of the assembly.

As illustrated in FIGS. 1, 3 and 4, in a particularly advantageous embodiment, the chair 10 includes a quartet of molded plastic leg glides 30, each having a rounded lower end 32, and an elongated, tapering upper end 34 that is dimensioned to fit snugly into the opening at the lower end of each of the chair legs 22 a, 22 b. The upper end 34 of each of the leg glides 30 plugs into a respective chair leg opening, where it is retained in a frictional fit, as illustrated in FIG. 3. The leg glides provide a finished appearance to the lower ends of the chair legs, and they enable the chair to be to be slid on the surface of a floor without marring it.

As illustrated in FIGS. 1 and 6-8, the seat module 14 comprises a rigid molded composite seat base 36 having a plurality of die-cut or saw-cut foamed elastomer, e.g., polyurethane, cushion layers bonded to it. In the particular embodiment illustrated, there are two foamed elastomer cushion layers, a lower cushion layer 38 a and an upper cushion layer 38 b bonded to the lower cushion layer 38 a. The upper cushion layer 38 b includes a nose piece 40 that laps down over the front edge of the lower cushion layer 38 a and the front nose portion 26 of the frame module 12. The upper and side surfaces of the cushion layers 38 a, 38 b are covered by a woven fabric upholstery covering 42 that laps over the front, sides and back of the seat base 36 and the cushion layers 38 a, 38 b, and the whole assembly is attached atop the substantially horizontal portions of the tubular members 18, 20 of the frame by conventional threaded fasteners (not shown) that extend through the bottom of the frame.

As illustrated in the drawings, and particularly FIGS. 11A-11D, the novel back module 16 of the chair 10 comprises an arcuate, generally rectangular, molded back base element 44 having relatively thin, substantially solid back and side walls 46 and 48, and a front face 50 that is formed as a shallow concavity, like a shallow tray. In one advantageous embodiment, the back base element 44 is molded from a rugged plastic, e.g., ABS. An intersecting, upstanding web structure 52 is molded into the back base element 44 to extend from the back wall 46 to the open front face 50 thereof, like an egg crate. The web structure 52 stiffens and reinforces the back base element 44 without substantially increasing its weight.

The back base element 44 also includes a bilateral pair of tubular receptacles or channels 54 (see FIG. 13) having open bottom ends and closed top ends. These receptacles or channels 54 have a cross-sectional configuration that corresponds to that of the upstanding stiles 24 of the frame module 12, and they are located so as to receive the stiles 24 when the back base element 44 is slid down over the stiles 24 to mount the back module 16 firmly to the frame module 12, as sequentially illustrated in FIGS. 9A-9D and 20. The back module 16 is then locked onto the frame module 12 by conventional fasteners (not shown), such as screws, that extend through respective ones of the two lateral side walls 46 of the back base element 44 and into the stiles 24. The channels 54 enclose and conceal the styles 24 when the back module 16 is installed, so that the styles 24 can be hidden when the back base element 44 is covered by a fabric covering, as discussed below.

The back module 16 further comprises a lower lumbar support element 56 having a lower end 58 that is substantially straight, and an upper end 60 that has a curvature that matches the arcuate curvature of the front face 50 of the back base structure 44 (see FIGS. 15-18). The lower lumbar support element 56 has a substantially continuous front face 62 and a rear face 64 on which is formed a plurality of stiffening webs 65, in a manner similar to the front face 50 of the back base element 44. As in the case of the back base element 44, the lower lumbar support webs 65 add considerable stiffness to the lower lumbar support element 56 without a corresponding increase in its weight. As illustrated in the drawings, the lower lumbar support element 56 attaches to the lower portion of the front face 50 of the back base 44 by means of a plurality of molded resilient snaps, or tabs 66 that extend rearwardly from the rear face 64 of the lumbar support element 56. The tabs 66 fit into corresponding slots 68 formed in the back base element 44 (see FIG. 11B) in a snap-in, over-center locking engagement. The front face 62 of the lower lumbar support element 56 is covered with a fabric upholstery 70 that laps around its edges and back face, as shown in FIGS. 1 and 6.

As also illustrated in FIGS. 1 and 6, the back module 16 further comprises main back cushion 72 attached to the upper portion of the front face 50 of the back base element 44, and an upper lumbar cushion 74 attached to the front face 50 just below the main back cushion 72. Both the main cushion back 72 and the upper lumbar cushion 74 are preferably made of a foamed elastomer, and they are advantageously attached to the front face 50 of the back base element 44 by a suitable adhesive. The upper lumbar cushion 74 thus is located between the main back cushion 72 and the lower lumbar support element 56, whereby the upper lumbar cushion 74 and the lower lumbar support element 56 will support the upper and lower lumbar regions, respectively, of a person (not shown) who sits in the chair.

The cushions, 72, 74 and the back surface 46 and sides 48 of the back base element 44 are covered in a fabric upholstery 76 (see FIGS. 1 and 6) that includes a pair of tack strips 78 (see FIG. 5), each with a plurality of upstanding tack fasteners 80 that pierce the rear surface of the back base element 44 to secure the back upholstery 76 thereon, such that the upstanding chair stiles 24 are thereby entirely hidden from view, and the entire seat back module 16 presents a clean, finished, decorative appearance.

It will be appreciated by those skilled in the pertinent arts that many modifications, substitutions and variations can be made in the materials, methods, and configurations of the stackable chair of the invention without departing from its spirit and scope. Accordingly, the scope of the present invention should not be limited to that of the particular embodiments described and illustrated herein, as these are merely exemplary in nature. 

1. A chair, comprising: a first frame member forming a first front chair leg and first rear chair leg joined by a first seat side rail; a second frame member forming a second front chair leg and a second rear chair leg joined by a second seat side rail; a third frame member having first and second side portions respectively joined to the first and second seat side rails, a transverse front nose portion, and a pair of upwardly-extending back stiles; a seat module assembly attached to the first and second seat side rails; and a back module assembly having a pair of channels configured and located so as to receive the stiles, whereby the back module assembly is attachable to the styles.
 2. The chair of claim 1, wherein the back module assembly comprises: a back base element having the channels formed therein and having a lower portion; and a lower lumbar support element attached to the lower portion of the back base element.
 3. The chair of claim 2, wherein the back base element is molded from a rigid plastic material.
 4. The chair of claim 3, wherein the back base element has a concave front face.
 5. The chair of claim 3, wherein the back base element is formed with an integral structural webbing.
 6. The chair of claim 4, wherein the back module further comprises: a main back cushion attached to the front face of the back base element; and an upper lumbar cushion attached to front face of the back base element between the main back cushion and the lower lumbar support element.
 7. The chair of claim 1, wherein the seat module comprises: a rigid seat base; a lower cushion layer; and an upper cushion layer bonded to the lower cushion layer.
 8. The chair of claim 7, wherein lower cushion layer includes a front edge, and wherein the upper cushion layer includes a nose piece that laps down over the front edge of the lower cushion layer and the transverse front nose portion of the third frame element.
 9. The chair of claim 1, further comprising: a front torsion bar connecting the first and second front legs; and a rear torsion bar connecting the first and second rear legs.
 10. A chair, comprising: a first frame member forming a first front chair leg and first rear chair leg joined by a first seat side rail; a second frame member forming a second front chair leg and a second rear chair leg joined by a second seat side rail; a third frame member having first and second side portions respectively joined to the first and second seat side rails, a transverse front nose portion, and a pair of upwardly-extending back stiles; a seat module assembly attached to the first and second seat side rails; and a back module assembly, comprising: a back base element having a pair of channels formed therein configured and located so as to receive and conceal the stiles, whereby the back module assembly is attachable to the stiles along the channels, the back base element having a lower portion; and a lower lumbar support element attached to the lower portion of the back base element.
 11. The chair of claim 10, wherein the back base element is molded from a rigid plastic material, and has a concave front face that includes an integral structural webbing.
 12. The chair of claim 11, wherein the back module further comprises: a main back cushion attached to the front face of the back base element; and an upper lumbar cushion attached to front face of the back base element between the main back cushion and the lower lumbar support element.
 13. The chair of claim 10, wherein the seat module comprises: a rigid seat base; a lower cushion layer; and an upper cushion layer bonded to the lower cushion layer.
 14. The chair of claim 13, wherein lower cushion layer includes a front edge, and wherein the upper cushion layer includes a nose piece that laps down over the front edge of the lower cushion layer and the transverse front nose portion of the third frame element.
 15. The chair of claim 10, further comprising: a front torsion bar connecting the first and second front legs; and a rear torsion bar connecting the first and second rear legs.
 16. A chair back module assembly for attachment to a chair frame having a pair of upstanding stiles, comprising: a back base element having a pair of channels formed therein configured and located so as to receive and conceal the stiles, whereby the back module assembly is attachable to the stiles along the channels, the back base element having a lower portion; and a lower lumbar support element attached to the lower portion of the back base element.
 17. The chair back module assembly of claim 16, wherein the back base element is molded from a rigid plastic material, and has a concave front face that includes an integral structural webbing.
 18. The chair back module assembly of claim 17, further comprising: a main back cushion attached to the front face of the back base element; and an upper lumbar cushion attached to front face of the back base element between the main back cushion and the lower lumbar support element.
 19. The chair back module assembly of claim 18, further comprising a fabric covering that covers main back cushion, the upper lumbar cushion, and the lower lumbar support element.
 20. The chair back module assembly of claim 19, wherein the fabric covering includes a pair of tack strips including a plurality of tacks that are located and oriented to attach the fabric covering to the back base element. 